NetBSD/sys/arch/sparc/include/lock.h

107 lines
3.5 KiB
C

/* $NetBSD: lock.h,v 1.6 1999/07/27 23:45:14 thorpej Exp $ */
/*-
* Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Paul Kranenburg.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _MACHINE_LOCK_H
#define _MACHINE_LOCK_H
/*
* Machine dependent spin lock operations.
*/
#if defined(_KERNEL)
#include <sparc/sparc/asm.h>
/*
* The value for SIMPLELOCK_LOCKED is what ldstub() naturally stores
* `lock_data' given its address (and the fact that SPARC is big-endian).
*/
#undef SIMPLELOCK_LOCKED
#define SIMPLELOCK_LOCKED 0xff000000
static void cpu_simple_lock_init __P((__volatile struct simplelock *));
static void cpu_simple_lock __P((__volatile struct simplelock *));
static int cpu_simple_lock_try __P((__volatile struct simplelock *));
static void cpu_simple_unlock __P((__volatile struct simplelock *));
static __inline__ void
cpu_simple_lock_init (alp)
__volatile struct simplelock *alp;
{
alp->lock_data = SIMPLELOCK_UNLOCKED;
}
static __inline__ void
cpu_simple_lock (alp)
__volatile struct simplelock *alp;
{
/*
* If someone else holds the lock use simple
* reads until it is released, then retry the
* atomic operation. This reduces memory bus contention
* becaused the cache-coherency logic does not have to
* broadcast invalidates on the lock while we spin on it.
*/
while (ldstub(&alp->lock_data) != SIMPLELOCK_UNLOCKED) {
while (alp->lock_data != SIMPLELOCK_UNLOCKED)
/*void*/;
}
}
static __inline__ int
cpu_simple_lock_try (alp)
__volatile struct simplelock *alp;
{
return (ldstub(&alp->lock_data) == SIMPLELOCK_UNLOCKED);
}
static __inline__ void
cpu_simple_unlock (alp)
__volatile struct simplelock *alp;
{
alp->lock_data = SIMPLELOCK_UNLOCKED;
}
#endif /* _KERNEL */
#endif /* _MACHINE_LOCK_H */